Lifting jack



C.V M. MARKHAM.

LIFTING JACK.

APPLICATION FILED AuG.s0. I9I9.

Patnted Mar. 28, 1922.

CHARLES IVI. vllvABlI(IAllf, CLF-MILVAUKEE, WISCONSIN.

' LIFTING JACK.

ratones.

Specification of Letters Patent.

rarement Mar. es, reza Application filed August 30,`1919.Y Serial No. 320,752.

To all -fwlwm t may concern.

Y Be it known that l, CHARLES M. MARKHAM, a citizen of the United States, and resident of Milwaukee, in the county o1 Milwaukee and State of l/Visconsin, have invented new and useful Improvements in Lifting Jacks, otwhich the following is a description, reterence being had to the accompanying drawings, which are a part oi' this specication.

,This invention relates to improvements in lifting jacks more particularly, although not solely, adapted for supporting concrete work during construction. Y

It is one of the objects oi' the present invention to provide a mechanism for concrete construction which is adapted for jacking up and supporting beams, girders, iioor plates, concrete forms, machinery, etc.

A further object of the invention is to provide a lifting jack which has a positive Y means for clamping the liifting merecerV preparatory to lli-'ting the same and which means engages the lifting member at a plurality of points. v

A further obj ect of the invention is to provide a lifting jack having a toggle connection between the clamping' members and the other parts. A further object of the invention is to provide a lifting jack in which the desired vertical adjustment may be quickly attained or the parts released for removal from the completed structure, andturtherinore that the parts of the jack may be easily separated ior convenience in packing. j

A further. object or' the invention is to provide a .lifting jack which is of simple construction,- is strong and durable and is well adapted for the purpose desired.

Viththe above and other objects in view, the invention consists of the'improved lifting jack and its parts and combinations set forth in the., claims, and all equivalents thereof. i y lvIn the accompanying drawing in which the same reference characters indicate the same parts in all of the views:

Fig. 1 is a side view of the improved lifting jack; parts ofthe jack being removed to shorten the view. j

Fig. 2 is a vertical sectional view thereof; and

F ig. 8 is a transverse sectional view thereof taken on line 3 3 of Fig. 1. Y

Referring to the drawing the numeral 5 indicates a tubular standard which is threaded to a base portion 6 at its lower end and to a tubular upper extension portion T at its upper end. The extension portion is formed with an annular shoulder 8 for supporting a releasing collar 9 and a tubular head portion 10 which rests upon the collar 9. `Said headl portion is provided with opposite radially extending ears 11 to which are connected inwardly and upwardly inclined toggle links 12. 'lransversely extending pins 13 pivotally connect the toggle links to the ears 1l, and the inner ends or" the links are pivotally connected to recessed portions- 11i of the clamping jaws 1d by pivot pins 15. 'ihe clamping jaws are of semicircular shape in horizontal plane and have threaded faces 16 which engage the opposite sides of the movable tubular member 17. Said movable member 17 isvertically slidably mounted in the tubular standard 5 and the exten` sion 7, and is maintained in adjusted position bythe clamping jaws 1A, the links 12 of which extendinwardly and incline slightly upwardlyto produce a clamping action when the jaws are engaging' the movable member 17. As thus constructed the greater the load on the movable member the greater the bite out the teeth, forming the thread of the jaws', on the movable member, and as the link connection permits all of the teeth of each jaw to engage the movable member, the said member will be rmly and positively clamped in adjusted position.

The'recesses 14: of the clamping jaws are so shaped as to limit their movement with relation to the links and thus maintain the jaws in proper position for engagement with the :movable member when the links 4are swung inwardly. Thelinks vmay be swung outwardly to disengage the jaws from the movable member when desired. The upper end portion oia the movable member is provided with a flanged cap 18 to :form an area of greater size thanthe said movable member for engaging the work to be supported thereby.

The movable member under load may be raised in any manner desired and when moved the linked jaws will automatically engage and maintain the movable member in adjusted position.

To provide for lowering and releasing the jack from its work the head portion l() is formed with downwardly extending lugs 19 having lower inclined faces 19 which rest-,upon the upstanding lugs 2O forming part of the collar 9. rThese last mentioned lugs have their Vupper faces inclined to correspond with the inclination of the lugs 19 and coact therewith. Gravity dogs 2l pivoted to the opposite side portions of the head 10 depend downwardly therefrom and enter recesses 22 formed in the releasing collar 9 to lock the head and the collar against relative rotation. Then it is desired to release the jack, the dogs are swung out of the recessed portions of the collar and the collar is given a partial rotation, which is facilitated by the inclined engaging faces of the lugs, and the lugs disengage each other and enter the spaces 23 on opposite sides of the lugs.

lVhen the lugs are thus disengaged the head, of which the upper lugs form al part, and the movable member will drop downwardly a suiiicient distance to disengage the work and the clamping jaws may then be raised to release the movable member and permit it to telescope into the standard and the jack to be removed from the work.

The head l() is provided with opposite fianged extensions 24 to permit the use of a lifting lever (not shown) for raising the movable member under load.

Y A semicircula-r spring stop member 25 partly surrounds the standard and is formed with an inturned end projection 25 which extends through an opening 26 in the standard and enters an annular recess 27 formed in the lower end of the movable member and engagesthe shoulder thereof to limit the outward movement of the movable memberand prevent the accidental removal thereof.

If it is desired to remove the said lInovable member the inwardly projectingend of the stop membermay be sprung slightly outwardly to disengage the shoulder and release the movable member.

In use, the jaclr is placed under the work t-o be supported and the movable member is elevated to engage and support the Work. While being elevated, the clamping jaws will automatically clamp and hold the movable member in adjusted position.

From the foregoing description, it will be seen that the lifting jack is of very simple construction and is well adapted for the purpose described.

What l claim asV my invention is:

l. A lifting jack, comprising a tubular standard having a shouldered part, a releasing collar carried by the standard and resting upon the shoulder, a head carried by the collar, a movable member connected to the standard and extending upwardly therefrom, a link pivotally connected to the head and extending inwardly therefrom, and a jaw member pivotally connected to the link and clampingly engaging the movable member.

2. A. lifting jack, comprising a tubular standard having a shouldered part, a releasing collar carried by the standard and resting upon the shoulder, a head connected to and vertically movable on the standard and carriedby the collar, a vertically movable member connected to the standard and extending adjustably upwardly therefrom, a linlr pivotally connected to the head and extending inwardly therefrom, means for locking the head to the collar, and a-jaw member pivotally connected to the linh and hav ing a toothed portion which clampingly engages the movable member.

3. ri lifting jack, comprising a tubular standard having a shouldered part, a releasing collar surrounding the standard and resting upon the shoulder, a head surrounding the standard and resting upon the collar, means for releasably'loclring the head to the collar, a vertically movable member slidably entering the standard and extending adjustably upwardly therefrom, links pivotally connected to thehead and extending inwardly therefrom, and aw members pivotallyV connected to the links and having toothed portions which clampingly engage the Vmovable member.

4l. A liftingjaclr, comprising a tubular standard having a shouldered part, a releas-l ing collar surrounding vt-he standard and resting upon the shoulder and having upstanding lugs', a head surroundingthe standard and resting upon the upstanding lugs of the collar, means releasably locking the head to the collar, links pivotally connected to the head and extending inwardly and up.- wardly therefrom, and jaw members-.pivotally connected toV and interposed between the inner ends of the linlcsand the'movable member and having toothed portions which clampingly engage said movable member. Y Y

5. A lifting jack, comprising a tubular standard having a shouldered part, a releasing collar surrounding the `standard and resting upon the shoulder and having upstanding lugs, a head surrounding the standard and resting upon the upstanding lugs of the collar, means releasably locking the head to the collar, links pivotally connected to the head and extending inwardly and upwardly therefrom, andV jaw members pivotally connected to and interposed between the inner ends of the linksV and the movable member and having inner curved and threaded faces which Vclampingly engage said movable member. Y

6. A lifting jack, comprising a tubular standard having a shouldered part, a releasing collar surrounding the standard and resting upon the shoulder and having upstanding lugs, a head surrounding the standard and having downwardly extending lugs which rest upon the lugs of the collar in one position of adjustment of the collar and eX- tend between the lugs in another adjustment, means for releasably locking the head and extending inwardly and upwardly therefrom, and jaw members pivotally connected to the inner end portions of the links and having inner curved and toothed faces which clampingly engage the movable member.

7. A lifting jack, comprising a tubular standard having a shouldered part, a releasing collar surrounding the standard and resting upon the shoulder and having upstanding lugs and recessed portions, a head surrounding the standard and having downwardly extending lugs which rest upon the lugs of the collar in one position of adjustment of the collar, and extend between the lugs in another adjustment, locking dogs pivotally connected to the head and entering the recessed portions, links pivotally connected to the head and extending inwardly and upwardly therefrom, and jaw members pivotally connected to the inner. end portions of the links and having inner toothed portions which clampingly engage a comparatively considerable area of the surface of the movable member.

8. A lifting jack, comprising a tubular standard havinga shouldered part,a releasing collar carried by the standard and resting upon the shoulder, a head connectedl to and vertically movable on the standard and carried by the collar, a vertically movable member connected to the standard and extending adjustably upwardly therefrom, means for limiting the upward movement of the movable member, a link pivotally connected to the head and extending inwardly therefrom, means for locking the head to the collar, and a jaw member pivotally connected to the link and having a toothed portion which clampingly engages the movable member.

9. A lifting jack, comprising a tubular standard having a shouldered part, a releasing collar carried by the standard and resting upon the shoulder, a head connected to and vertically movable on the standard and carried by the collar, a vertically movable member connected to the standard and extending adjustably upwardly therefrom, said movable member having an annular recess, a spring member extending partly around the standard and engaging the annular recess to limit the upward movement of the movable member, a link pivotally connected to the head and extending inwardly therefrom, means for locking the head to the collar, and a jaw member pivotally connected to the link and having a toothed portion which clampingly engages the movable member.

l0. The combination with a lifting jack having a tubular Standard and a vertically movable telescoping member provided with an annular recess adjacent its lower end to form a shoulder, of a spring member extending partly around the standard and having one end portion extending through an opening in the standard and provided with an inner beveled end adapted to enter the annular recess' and engage the shoulder to limit the upward movement of the movable member.

In testimony whereof, I aiiix my signature.

CHARLES M. MARKHAM. 

